Our prior patent application PCT/SE88/00691, filed on Dec. 20, 1988 and published after the filing date of this application, relates to a group of novel compounds which are useful in the treatment, acute as well as long term, of cardiac arrhythmias of diverse etiology. Among the compounds included in the group of compounds disclosed in said application is the compound 4-[3-[ethyl[3-(propylsulfinyl)propyl]amino]-2-hydroxypropoxy]-benzonitrile having the formula I ##STR1## which can be obtained as a stereoisomeric mixture as well as in the form of the different isomers; the following two stereoisomers are mentioned in the said application:
4-[3-[ethyl[3-(propylsulfinyl)propyl]amino]-2(R)-hydroxypropoxy]-benzonitri le, PA0 4-[3-[ethyl[3-(propylsulfinyl)propyl]amino]-2(S)-hydroxypropoxy]-benzonitri le. PA0 4-[3-[ethyl[3-((R*)-propylsulfinyl)propyl]amino]-2(R)-hydroxypropoxy]-benzo nitrile, PA0 4-[3-[ethyl[3-((S*)-propylsulfinyl)propyl]amino]-2(R)-hydroxypropoxy]-benzo nitrile, PA0 4-[3-[ethyl[3-((R*)-propylsulfinyl)propyl]amino]-2(S)-hydroxypropoxy]-benzo nitrile PA0 4-[3-[ethyl[3-((S*)-propylsulfinyl)propyl]amino]-2(S)-hydroxypropoxy]-benzo nitrile, and pharmaceutically acceptable salts thereof,